On spinodal decomposition in alnico - A transmission electron microscopy and atom probe tomography study

Zhou, Lin; Guo, Wei; Poplawsky, J. D.; Ke, Liqin; Tang, Wei; Anderson, I. E.; Kramer, M. J.

doi:10.1016/j.actamat.2018.04.042

Title: On spinodal decomposition in alnico - A transmission electron microscopy and atom probe tomography study

Journal Article · Thu Apr 26 00:00:00 EDT 2018 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2018.04.042· OSTI ID:1454574

Zhou, Lin ^[1]; Guo, Wei ^[2]; Poplawsky, J. D. ^[2]; Ke, Liqin ^[1]; Tang, Wei ^[1]; Anderson, I. E. ^[1]; Kramer, M. J. ^[1]

Ames Lab., Ames, IA (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Alnico is a prime example of a finely tuned nanostructure whose magnetic properties are intimately connected to magnetic annealing (MA) during spinodal transformation and subsequent lower temperature annealing (draw) cycles. Using a combination of transmission electron microscopy and atom probe tomography, we show how these critical processing steps affect the local composition and nanostructure evolution with impact on magnetic properties. The nearly 2-fold increase of intrinsic coercivity (Hci) during the draw cycle is not adequately explained by chemical refinement of the spinodal phases. Instead, increased Fe-Co phase (α1) isolation, development of Cu-rich spheres/rods/blades and additional α1 rod precipitation that occurs during the MA and draw, likely play a key role in Hci enhancement. Chemical ordering of the Al-Ni-phase (α2) and formation of Ni-rich (α3) may also contribute. Unraveling of the subtle effect of these nano-scaled features is crucial to understanding on how to improve shape anisotropy in alnico magnets.

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Research Organization:: Ames Laboratory (AMES), Ames, IA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE Office of Energy Efficiency and Renewable Energy (EERE)

Grant/Contract Number:: AC02-07CH11358; AC05-00OR22725

OSTI ID:: 1454574

Alternate ID(s):: OSTI ID: 1495986; OSTI ID: 1548461

Report Number(s):: IS-J-9646; PII: S1359645418303197

Journal Information:: Acta Materialia, Vol. 153, Issue C; ISSN 1359-6454

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 14 works

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References (15)

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36 MATERIALS SCIENCE
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